Spray apparatus

ABSTRACT

A method and apparatus for distributing a flowable material onto a base surface and wherein a rotary member is rotatably supported concentrically within a mask, a flowable material supply to the rotary member deposits said material on the rotary member and said material is centrifuged uniformly from the periphery of the rotary member, said mask has slots through which selected segments of centrifuged material can pass while the spray segments striking the inside of the mask between the slots is arrested to achieve a spray pattern on the base surface in accordance with the arrangement of slots in the mask. In a preferred embodiment a second rotary member is located beneath the mask and material arrested by the mask constitutes a material supply to the second rotary member.

This invention relates to a method and apparatus for distributingflowable material and has particular application to the distribution ofchemical aids onto, or into, growing crops.

Many chemical aids, for example, weed killers, insecticides, and growthpromotion aids, are supplied to the farmer in liquid form and other aidssupplied in powder or granule form are best distributed as a solution orsuspension in a medium, generally water, so that most aids are appliedto the crop as a liquid. The convention liquid distributing means is thenozzle and, in practice, a liquid spraying equipment would comprise aplurality of nozzles arranged to spray liquid in an overlapping spraypattern to ensure covering all the ground traversed by the sprayingequipment.

A serious disadvanage of the conventional nozzle is that it produces awide range of droplet sizes, the small droplets tend to drift away fromthe target area in ambient air currents and the large droplets contain aexcessive amount of chemical aid and are therefore wasteful. Further, itis extremely difficult to obtain uniform performance from a plurality ofnozzles and the actual spray pattern of most nozzles is unsuitable fordistributing a chemical aid uniformly over the target area.

Because of the above difficulty farmers find it necessary to dilute thechemical aid, often with up to 50 times its volume, of water, and thisnot only places a great demand for water at the treatment location butit also increases the weight of the spray equipment to the detriment ofthe crop.

The present invention seeks to provide a method and apparatus fordistributing a flowable material in accordance with a desired spraypattern with a minimum of loss and wastage of the material within thetarget area.

According to the present invention a method for distributing a flowablematerial comprises the steps of centrifuging the material from aperipheral region of a rotary member to produce a spray patternsubstantially uniformly disposed about the axis of rotation of therotary member and interrupting the free flow of material in the uniformspray pattern at a plurality of locations spaced about the axis ofrotation of the rotary member to establish a spray pattern defined byselected sectors of the initial spray pattern.

Preferably the interruption of free material centrifuged from the rotarymember is effected by a mask, having a plurality of slots or openingsthrough which the material can pass and, in one method in accordancewith the invention, the material which does not pass through the mask iscollected therefrom and returned to the rotary member.

Preferably two rotary members are provided, at least one of which isallowed to distribute substantially the whole of the flowable materialsupplied thereto substantially uniformly about its axis of rotation, andthe material centrifuged from the other rotary member is obstructed at anumber of locations spaced about its axis whereby, said other memberimposes a predetermined spray pattern on the spray pattern of the firstrotary member.

Preferably the two rotary members are arranged for rotation about acommon axis and preferably the obstructed flowable material is collectedand constitutes a flowable material supply for the member which does nothave its spray pattern interrupted.

According to one aspect of this invention a method of applying aflowable material onto a base in accordance with a desired distributionpattern comprises the steps of supplying flowable material to a rotarymember rotating about an axis substantially vertical to said basesurface, allowing the rotary member to centrifuge flowable materialsupplied thereto from a peripheral region thereof to obtain a spraypattern of substantially uniform particle or droplet size uniformlyabout the periphery of the rotary member, displacing the rotary memberover the base and interrupting the uniform spray pattern at a number oflocations spaced about the axis of the rotary member but fixed relativeto the direction of displacement of said member to obtain from theuninterrupted parts of the spray pattern a desired distribution offlowable material over the base surface transverse to the said directionof travel.

Preferably more than one rotary member is provided for distributingflowable material therefrom and all of said rotary members are displacedin the direction of travel at the same speed.

It has been found by experiment that for a given diameter of theperipheral region of a rotary member and a given viscosity of a liquidthe rotational speed can be readily determined to produce dropletswithin a relatively narrow range of sizes and thus the best droplet sizefor hitting the base surface can be obtained to give maximum efficientuse of the material.

Further, as the material is centrifuged rather than passed through thesmall openings in nozzles, liquid chemicals can be distributed withoutbeing diluted for with the minimum of dilution and many materials whichcould not normally be sprayed by conventional spray equipment can bedispersed by the rotary members proposed by the present invention.

When the apparatus is to be used to spray a base surface and the rate ofdisplacement of the apparatus over the base surface is not constant,such as in the spraying of crops, the rotary member or members can berun at constant speed and the supply of flowable material theretoregulated in accordance with the ground speed whereby the base surfacecan be sprayed in accordance with a desired pattern independantly of theactual rate of displacement between the apparatus and the base surface.

According to another feature of the invention apparatus for distributingflowable material comprises a rotary member and a mask substantiallyconcentric with the rotary member and having a plurality of slotsaligned with the rotary member to permit only part of the materialcentrifuged from the rotary member to pass therethrough.

Preferably the apparatus includes means for rotating the rotary memberand a supply duct for directing flowable material onto or into therotary member.

Preferably the rotary member comprises a disc mounted on a shaft forrotation therewith and the mask includes an annular section having saidslots therein and a conical section beneath said annular section.

Preferably said rotary member and said mask form a spray assemblymounted on a carriage for displacement relative to a base surfacewhereby the assembly can be given a positive displacement relative tothe base surface and, when the assembly is to be used for agriculturalpurposes, the carriage is provided with wheels and adapted to be pushedor pulled over a field to be sprayed by the assembly.

Preferably a second rotary member comprising disc is mounted forrotation relative to the first rotary member and the second disc isadapted to receive flowable material thereonto and to centrifuge theflowable material therefrom in a spray pattern substantially uniformabout the axis of the said second disc.

The second rotary member is preferably not used in conjunction with amask and is so aligned with the masked member that when both members areoperational to dispense flowable material the spray pattern of themasked member is superimposed on the spray pattern of the second member.

Preferably the two members are mounted for rotation about a common axisand preferably rotate in the same direction of rotation.

When the two members are axially aligned, of equal diameter, and are torotate in the same direction, they may be mounted on a common shaft.

Preferably the masked member is located above the second member andflowable material caught by said mask is directed onto the secondmember.

Preferably the sum total of the peripheral lengths of all the slots isequal to the sum total of the peripheral length of the mask materialbetween the slots.

In a preferred embodiment in accordance with the invention a pluralityof rotary member and mask assemblies, each including a second rotarymember, are arranged in spaced relationship on a carriage adapted to betowed by a tractor and the carriage includes a drive means for rotatingall the rotary members at substantially constant and uniform speeds.

The carriage also includes a flowable liquid supply tank with pipes forducting flowable liquid to each rotary member and a metering device,controlled by the forward motion of the carriage, for adjusting thesupply of flowable material in dependence upon the speed of thecarriage.

When the, or each, rotary member comprises a disc said disc may be madefrom any metal or plastics material which does not affect the flowablematerial and which can be wetted by said flowable material. The disc maypresent a flat or curved i.e. bowl shaped, flowable materialcentrifuging surface.

The mask may have fixed or adjustable slots therein and preferably themask is arranged for at least limited rotation relative to the axis ofthe rotary member to allow the mask to be adjusted relative to a desireddirection of displacement for the assembly.

The mask may include a pin adjacent to the leading edge of each slot toprevent particles of droplets of centrifuged flowable material fromstriking said leading edge. Alternatively the trailing edge of each masktongue between adjacent slots may be inwardly turned or the whole ofeach tongue may be deflected to be substantially perpendicular to thepath of particles or droplets impinging thereon when the apparatus isoperational.

The invention will now be described further by way of exanple withreference to the accompanying drawings in which:

FIG. 1 shows a plan view of a rotatable member and mask assembly;

FIG. 2 shows a side view of the assembly illustrated in FIG. 1;

FIG. 3 shows a cross section through the assembly on the line 'A--A' inFIG. 1;

FIG. 4 shows a plan view of a towed carriage for mounting a plurality ofassemblies and;

FIG. 5 shows a side view of the field spray equipment shown in FIG. 4.

The assembly illustrated in FIG. 1, 2 and 3, comprises a shaft 12supported vertically by a bearing 13 and rotable by a power unit,generally indicated by number 14. A rotary member, defined by a disc 15,is secured on the shaft 12 for rotation therewith and a mask 16,comprising an annular section 16a and a tapered section 16b beneathsection 16a, is supported by a bracket 19 so as to lie concentric withthe axis of shaft 12.

The annular section 16a has a plurality of open ended slots 16c thereinextending parallel to the axis of shaft 12 and of differingcircumferential widths and spacings, for reasons which will becomeapparent hereinafter. The mask 16 is supported from a carriage, such asthe carriage 18 in FIGS. 4 and 5, by a bracket 19 and the bearing 13 andpower unit 14 are supported from the carriage 18 by brackets 20 and 21respectively.

When the assembly is operational power unit 14 rotates shaft 12, andthereby disc 15, at a substantially uniform speed relative to mask 16. Aflowable liquid, such as weedkiller, is delivered onto the top surfaceof the disc 15 by way of a supply pipe 22, which includes a meteringdevice 23, and by carefully regulating the rate of delivery of liquidand the rotational speed of the disc 15 droplets, of substantiallyuniform size, are centrifuged from the periphery of the disc 15.

With uniform distribution of the liquid on the disc a substantiallyuniform release of droplets about the periphery of disc 15 is obtainedand, if the assemble is given a uniform displacement over a base surfaceand the mask 16 is omitted, the spray pattern from the disc 15 wouldresult in an uneven distribution of the liquid transverse to thedirection of displacement. Thus, the deposition of the liquid wouldincrease in density towards the sides of the path covered by the spraypattern.

By providing the mask 16 with a plurality of slots 16c therein only partof the liquid centrifuged from the disc 15 is released from the assemblythrough the slots 16c and the liquid caught by the mask section 16aflows down into the conical section 16b.

Thus, by carefully selecting the circumferential position and width ofeach slot a desired deposition pattern can be obtained across the pathcovered by the spray and, for example, a substantially uniformdistribution, light side with heavy centre distribution, heavy side withlight centre distribution, or graduated distribution can be obtained.

It will be observed that the droplets are released tangentially from theperiphery of the disc 15 and those droplets directed towards the leadingedge of each slot 16c can, upon striking such an edge, splatter andbreak up into small droplets some of which can pass through the adjacentslot to the detriment of the spray pattern. To prevent such dropletsissuing from the mask a rod 24 is secured inwardly of and adjacent theleading edge of each slot to protect said leading edge and prevent therelease of droplets after such droplets have engaged the mask.

In an alternative embodiment (not shown) the leading edge of each slotmay be turned inwardly to prevent the release of splattered dropletsfrom the slots 16c and in a further embodiment the mask tongues betweenthe slots 16c can be deflected so as to increase the angle between theinner mask surface and the droplets impinging thereon.

As stated hereinbefore the droplets obstructed by the annular masksection 16a flow down into the conical section 16b and this liquid canbe returned for resupply via supply pipe 22. In the illustrated examplehowever the conical section 16b has an open bottom and the liquid insection 16b falls through the open bottom onto a second disc 25 securedon shaft 12.

The spray pattern produced by the unmasked disc 25 will of course resultin an uneven distribution of liquid across the path being traversed andin such a case the slots 16c in the mask 16 are arranged to develop aspray pattern from the rotary disc and mask assembly which, whensuperimposed on the spray pattern of the unmasked disc, produces thedesired liquid distribution on pattern.

As will be seen from FIG. 1 the sum total of the circumferential widthsof all the slots 16c is substantially equal to the sum total of thecircumferential widths of the mask tongues between the slots whereby theliquid dispensed through the mask is approximately half the total liquiddispensed from the disc 15.

FIGS. 4 and 5 illustrate a field spray equipment in accordance with theinvention and wherein the carriage 18 comprises transverse beams 31mounted on a wheeled chassis 32 which chassis 32 includes an "A" frame33 by which the carriage assembly 31, 32, 33, can be attached to atowing vehicle, defined by tractor 34.

The carriage 18 supports five spray assemblies of the type shown inFIGS. 1, 2 and 3 in spaced relationship and the pitch of the assembliesand the spray patterns selected therefore are such that a substantiallyuniform liquid distribution across the whole of the ground traversed bythe carriage and influenced by the spray apparatus is obtained.

The five assemblies on the carriage 18 may be driven by individual powerunits but are preferably driven by a single motor (not shown) mounted onthe chassis and driving the separate assemblies through chain drives orshaft and pinion drives and by these latter arrangements all theassemblies can be rotated at substantially uniform speeds.

Again, a separate liquid supply can be provided for each assembly or, asillustrated, a common supply tank 35 may be provided with supply pipes22 to each assembly. Further a metering device 23 can be provided foreach supply pipe 22 or, as illustrated in FIGS. 4 and 5, a singlemetering device 36 may be provided at the outlet of tank 35 and saidmetering device 36 controlled by a chain drive 37 to a land wheel 38 ofthe chassis 32. By this means the volume of liquid delivered to theassemblies becomes dependant upon the land speed of the spray equipmentand the desired distribution of liquid thus becomes independent of theland speed of the equipment.

The illustrated equipment also includes air compressors 39 mounted onchassis 32 and adapted to discharge air through nozzles 40 mountedbefore and after each spray assembly relative to the direction ofdisplacement of the apparatus. The nozzles 40 discharge air flowsdownwardly to assist penetration and distribution of the droplets withinthe crop.

The invention has been described with reference to a specificembodiment. It will be appreciated that the invention is not limitedthereto but rather is limited only by the scope of the appended claims.

I claim:
 1. A method for distributing a flowable material onto a basesurface comprising the steps of: centrifuging the material from aperipheral region of a rotary member to produce a spray patternsubstantially uniformly disposed about the axis of rotation of therotary member; interrupting the free flow of material in the uniformspray pattern at a plurality of locations spaced about the axis ofrotation of the rotary member to establish a spray pattern defined byselected sectors of the initial uniform spray pattern; and transversingthe rotary member over the base surface with said locations fixedrelative to the direction of displacement over the base surface toobtain from the interrupted spray pattern a desired distribution offlowable material over the base surface transverse to the said directionof displacement.
 2. A method as claimed in claim 1 and including thesteps of continuously supplying flowable material at a substantiallyuniform rate, rotating said rotary member at a substantially uniformrate, and transversing the rotary member over the base surface at asubstantially uniform height and rate of displacement to obtain asubstantially uniform distribution of material over the base surface inthe direction of displacement.
 3. A method as claimed in claim 1including the steps of regulating the rate of flowable material supplyto the rotary member in dependence upon the rate of displacement overthe base surface.
 4. A method as claimed in claim 3 including the stepof terminating the supply of flowable material to the rotary member whenthe peripheral speed of the rotary member falls below a predeterminedminimum speed.
 5. A method as claimed in claim 1 in which the materialinterrupted from the spray pattern at said locations is collected andreturned to the rotary member for re-distribution therefrom.
 6. A methodas claimed in claim 1 including the steps of collecting the materialinterrupted from the spray pattern at said locations, supplying saidcollected material to a second rotary member and centrifuging thematerial from said second rotary member to establish a spray patterntherefrom different from the interrupted spray pattern from the firstrotary member.
 7. A method as claimed in claim 6 in which the spraypattern from the second rotary member comprises an uninterrupteddistribution uniformly about the rotational axis of the second rotarymember.
 8. A method as claimed in claim 6 including the steps oflocating the second rotary member relative to the first rotary membersuch that the interrupted spray pattern of said first rotary member issuperimposed on the spray pattern of the second rotary member.
 9. Amethod as claimed in claim 6 wherein the volume of material distributedin the interrupted spray pattern is substantially equal to the volume ofmaterial distributed in the spray pattern from the second rotary member.10. A method as claimed in claim 1 including the further step ofregulating the rate of flowable material supply to the rotary member independence upon the peripheral speed of the rotary member.
 11. A methodfor distributing a flowable material over a substantially horizontalbase surface comprising the steps of supporting two disc-like rotarymembers of substantially uniform diameter on a common drive shaft withthe rotational axis of said shaft substantially vertical, said shaftpassing centrally through said rotary members and supporting saidmembers in vertically spaced relationship at substantially fixed heightabove said base surface, surrounding the highest one of said rotarymembers with a mask having slots therein, continuously displacing saidshaft and rotary members supported thereon over the base surface,supplying flowable material to the highest one of said rotary members,rotating the shaft, and thereby the two rotary members, at asubstantially constant peripheral speed sufficient to centrifuge thematerial supplied to the said higher rotary member uniformly from theperiphery thereof allowing free flow of material centrifuged from thesaid highest rotary member through the said slots in the mask,collecting the material centrifuged from the said highest rotary memberand arrested by the mask material between said slots, directing saidcollected material to a material supply for the lower rotary member andcentrifuging the material from said lower rotary member, whereby theinterrupted flow pattern from the first rotary member is superimposed onthe flow pattern from the lower rotary member to obtain a desireddistribution of material transverse to the direction of displacementover the base surface.
 12. A method as claimed in claim 11 and whereinthe rate of flow of material disbursed in the interrupted flow patternfrom the higher rotary member is substantially equal to the rate of flowof material from the lower rotary member.
 13. A method as claimed inclaim 11 wherein the interrupted spray pattern is arranged to produceacross the area of the base surface upon which the material is depositedlight side with heavy centre deposition of material or heavy side withlight centre deposition of material.
 14. A method as claimed in claim 11in which the interrupted spray pattern, when superimposed on the spraypattern from the second or lower rotary member, produces a substantiallyuniform distribution of material transverse to the direction ofdisplacement over the base surface.
 15. Apparatus for distributing aflowable material onto a base surface comprising a spray assemblyadapted to be supported above the base surface and including a rotarymember and a non-rotating mask substantially concentric with the rotarymember, said mask including means for permitting selected segments ofmaterial centrifuged uniformly from the rotary member to passtherethrough and for obstructing the remaining segments of centrifugedmaterial from passing therethrough whereby to establish an interruptedspray pattern distribution on said base surface, said permitting meansincluding a plurality of slots through said mask, said slots beingcircumferentially spaced around the entire periphery of said mask. 16.Apparatus as claimed in claim 15 in which said rotary member comprises adisc, one surface of which defines a material receiving surface for therotary member, with a peripheral wall upstanding from said surfacematerial receiving surface.
 17. Apparatus as claimed in claim 16 inwhich said peripheral wall extends outwardly from said surface to a freeedge and said free edge defines the edge from which material iscentrifuged.
 18. Apparatus as claimed in claim 16 in which the internalsurface of the peripheral wall is grooved and said grooves lie in planespassing through the rotational axis of the rotary member.
 19. Apparatusas claimed in claim 16 in which the free peripheral edge of theperipheral wall is notched.
 20. Apparatus as claimed in claim 15 inwhich the sum total of the peripheral lengths of all the slots in themask is equal to the sum total of the peripheral length of mask materialbetween the slots.
 21. Apparatus as claimed in claim 15 in which themask includes an annular section within which the rotary member islocated and said slots are limited to said annular section. 22.Apparatus as claimed in claim 15 in which the rotary member is made froma plastics material.
 23. Apparatus as claimed in claim 15 in which thespray assembly is mounted on a carriage which is capable of beingtransversed over said base surface, and which is capable of supportingthe assembly at a substantially constant height above the base surface,the rotational axis for the spray assembly being located substantiallyvertically.
 24. Apparatus as claimed in claim 16 in which means areprovided for supplying flowable material to the material receivingsurface of the disc, said means including a metering device forcontrolling the rate of flow of material to the rotary member and ashut-off device for terminating the flow of material to the disc whenthe disc speed falls below a predetermined level.
 25. Apparatus asclaimed in claim 15 in which duct means are provided for directingflowable material obstructed by the mask back to the rotary member. 26.Apparatus as claimed in claim 15 in which said rotary member is a firstrotary member and in which the spray assembly includes: a second rotarymember, a drive for rotating said second rotary member, and a duct forsupplying flowable material to said second rotary member.
 27. Apparatusas claimed in claim 26 in which the second rotary member hassubstantially identical dimensions as said first rotary member. 28.Apparatus as claimed in claim 26 in which the first and the secondrotary members are mounted on a common drive shaft.
 29. Apparatus asclaimed in claim 15 wherein said spray assembly is mounted on a carriagewhich is capable of being displaced over the base surface, said rotarymember being a first disc-like rotary member secured on a substantiallyvertical drive shaft, and wherein said mask surrounds said first rotarymember and includes an annular section with said slots therein, saidslots being aligned with said first rotary member, said mask including aconical section beneath said annular section, said spray assemblyincluding: a second rotary member secured on said drive shaft beneathsaid mask, a flowable material supply duct to the top surface of saidfirst rotary member, and a flowable material supply duct from the lowerregions of the conical section of the mask to said second rotary member.30. Apparatus as claimed in claim 15 in which the spray assemblycomprises an electric motor for rotating the rotary member within themask.
 31. Apparatus as claimed in claim 29 in which the carriageincludes means for rotating the drive shaft in a speed range dependentupon the viscosity of the flowable material, at which speed rangeflowable material is centrifuged from a peripheral edge of each rotarymember uniformly about the axis of rotation and of substantially uniformdroplet size.
 32. Apparatus as claimed in claim 31 in which said meansfor rotating the drive shaft is selected from the group consisting ofpneumatic, hydraulic, electrical or mechanical devices, the power sourcefor which is supported by the carriage.
 33. Apparatus as claimed inclaim 23 in which the carriage includes means for directing air blastsdownwardly onto spray patterns from the rotary members forwardly of andrearwardly of the spray assembly in the direction of displacement overthe base surface.
 34. Apparatus as claimed in claim 23 and wherein aplurality of spray assemblies are supported in spaced relationship onthe carriage.
 35. Apparatus as claimed in claim 15 in which the mask isrotatably adjustable about the axis of rotation for the rotary membertherein.
 36. Apparatus as claimed in claim 15 in which the rotary memberis made from a metal.
 37. Apparatus as claimed in claim 15 wherein saidslots are elongated and extend parallel to the axis of the rotarymember, some of said slots being of different circumferential widthsthan the circumferential widths of others of said slots.